Metal convolution tubing



March 10, 1959- M. H. NOVEMBER METAL CONVOLUTION TUBING 2 Sheets-SheetFiled March 10, 1955 IN V EN TOR. t ml/en March 10, 1959 M, H, OVEM ER2,876,801

METAL CONVOLUTIO N TUBING Filed March 10. 1955 2 Sheets-Sheet 2 IN V ENTOR. H1130? 1, HIV07211L6 er United States Patent 2,87 6,301 NIETAL CONVOLUTION TUBING Milton H. November, Corporations, Inc, Jersey Montclair,N. J., assignor to Breeze Union, N. J., a corporation of New Thisinvention relates to metal tubing and specifically to metal tubinghaving a convoluted wall for the purpose of imparting flexibility andother characteristics thereto.

It is well known to form metal tubing having a series of convolutionstherein, said convolutions being in the form of a plurality of paralleltroughs and crests or a plurality of helically disposed troughs andcrests. Presently known tubing is formed with identically shaped troughand crest sections and flexibility has been somewhat improved bycompressing the tubing longitudinally after its formation.

The above described tubing is prone to failure and unsatisfactorybehavior from several standpoints. Under high internal pressures thetubing tends to elongate and when so stretched fails to return to itsoriginal length. When so stretched the outside diameter of the tubing isdecreased. Where tubing is covered by woven braid the elongation of thetubing also stretches the braid, causing the tubing. As a result, thewall of the tubing may become flattened or ruptured. High internalpressures also tend to compress the convolutions of the tubing, therebycausing damage to the thin walled structure. I

Accordingly, it is an object of the present invention to provideconvoluted tubing structures which will withstand a greater amount ofpressure without excessive elongation.

Another object of the present invention is to provide a convolutedtubing structure of greater flexibility.

A further object of the present invention is to reduce peripheral damageto convoluted tubingfrom overlying braid structures or the like.

A still further object of the present invention isto provide convolutedtubing having a fairly smooth internal bore, so as to improve thepassage of fluids therethrough.

An object of the present invention is to provide convoluted tubing whichwill withstand greater amounts of pressure without wall damage.

A feature of the present invention is. its additional flex section,which results in less wall thinning during fabrication of the tubing.

Another feature of the present invention is its ability to withstandsharp bends without losing its smooth bore characteristics.

A further feature of the present invention is its trough form, wherebygreater pressures are withstood.

The invention consists of the construction, combination and arrangementsof parts as herein illustrated, described and claimed.

In the accompanying drawings forming a part hereof, there areillustrated six forms of embodiment of the invention, and in which:

Figure 1 is a view in side elevation, partially cut away, of a completeembodiment of one form of the present invention.

Figure 2 is a longitudinal fragmentary sectional view of a second formof the present invention.

Figure 3 is a longitudinal fragmentary view of a modi-- fication of theform shown in Figure 2.

Figure 4 is a longitudinal fragmentary view of a third embodiment of thepresent invention.

Figure 5 is a view similar tothat of Figure 4, showing the tubing in aflexed position.

Figure 6 is a longitudinal fragmentary view of conventional convolutedtubing, showing the manner in which an overlying braid structure bearsupon the outside diameter of the tubing structure.

Figure 7 is a longitudinal fragmentary view of a fourth embodiment ofthe present invention.

Figure 8 is a longitudinal fragmentary view of a fifth embodiment of thepresent invention.

Figure 9 is a fragmentary view taken on line 99 of Figure 8.

Figure 10 is a longitudinal fragmentary view of a sixth embodiment ofthe present invention.

Referring to the drawings and specifically to Figurev 1, 10 indicates alength of tubing formed from seamless tubing, helically wound and weldedtubing or lapped and welded tubing, all of which are well known in theart. The parallel-Walled tubing 10 is fed through suitable machineswhich form the wall of the tubing into a series of convolutionsgenerally indicated at 12.

Presently known convoluted tubing, best shown in Figure 6, consists of aseries of symmetrical crests and troughs. This tubing may be compressedto add flexi bility, but maintains its symmetry. It has been found,

however, that by varying the shape of the troughs and crests of thetubing in the. manner hereinafter set forth, the behaviorcharacteristics of the convoluted tubing may be substantially improved.

In the form of the invention shown in Figure Leach of the crests 13 ofthe convolutions 16 have been inverted so as to provide an additionalflex section 14 therein. In that. the flex sections 14 are inwardlydisposed toward the. central axis of the tubing they have been referredto as inverted. As a result of the additional flex section 14, severalsurprising advantages have been derived. When high fluid pressures arepresent Within the tubing 10, the said. tubing has. a tendency tostretch longitudinally and its outside diameter to contractdiametrically. When the troughs and crests of the tubing were of uniformshape the amount of such elongation was great and the degree of.recovery therefrom quite limited. The additional flax section 14,however, substantially increases the ability of the tubing to recoverits original dimensions aftersuch longitudinal extensions. Moreover, theinitial longitudinal extension is found to be less with the convolutionform shown inFigure 1.

Where tubing is covered with woven braid as in the practice, and.greatinternal pressure is applied, thev braid tends to crush the tubingas it is stretchedd'uring the elongation of the structure. As shown inFigure 6, the cononly a one point contact with As a result, thelikelihood of damage to the tubing at the crest is fairly great. Wherethe inverted flex section 14 is used and is covered by braid as shown inFigure 7, the points of contact between the crest and the braid 18 aredoubled, and the distance between said points of contact issubstantially reduced. As a result of the flex section 14 therefore, theability of the convoluted tubing to withstand the pressure of the braid18 is greatly increased. Moreover, since the form of the tubing shown inFigure 1 tends to have less longitudinal extension under pressure thanconventional convolution tubing, the pressure of the braid 18 is furtherreduced.

A further result achieved by the use of the flex sections 14 in theconvoluted tubing is an increase in flexibility. It has been found thatfor a convoluted tube of conven' tional construction and given amplitudeof convolution the braid 18 at each crest.

one may use a smaller amplitude or wall height in the Since the wallheight is less, there will be less and consequently a structure. wallthinning during manufacture, stronger structure.

In the embodiment of the invention shown in Figure 2, a fairly smallflex section trough 14, as compared with the amplitude of the maintrough 15 of the tubing 10 may be employed. This structure, while lessflexible than that of Figure 3, in which the amplitude of the flexsection 14 is greater, as indicated by the arrows a and b, isnevertheless cheaper to manufacture because it requires less material.It will therefore be seen that the inverted flex section is capable ofproducing a wide variety of performance characteristics withoutdeparting from the spirit of the invention.

Referring again to Figure 1, it will be seen thatthe troughs 15 aresomewhat flattened, whereas those illus trated in Figures 2 and 3 arearcuate. It has been found that the flattened form of trough 15 willwithstand greater pressure before collapsing.

As a further trough modification there is shown the form of Figure 4, inwhich an extremely flat surface 17 has been provided for the purpose ofboth increasing the resistance of the structure to pressure andimproving the smoothness of the internal bore of the tubing. As a resultof the combined flattened trough structure 17 and the use of theinverted flex section 14, the tubing form illustrated in Figure 4 may bebent as shown in Figure 5 without substantially decreasing thesmoothness of the bore.

. Referring to Figure 8, there is shown a further modification of thetrough form 15, whereby the convoluted tubings ability to withstandpressure is improved. In this form of the invention the troughs 15 areprovided with a series of dimples or ribs 16, which are pressed into themetal of the tubing forming the trough portion 16. These ribs 16 may beeither bent outwardly as shown in Figure 9, or pushed inwardly toachieve the same purpose, namely to prevent the trough 15 of the tubingfrom being collapsed under pressure. It will be apparent that thespacing of the ribs 16 and the size and shape thereof may be varied toachieve a wide variety of behavior properties. While the forms of thetubing shown in Figures 8 and 9 have not been longitudinally compressed,as for example those shown in Figures 4 and 5, it is within the purviewof the present invention-to compress these structures in order to impartgreater flexibility thereto.

The convoluted tubing form shown in Figure 10 combines the rib structure16 of the trough with the inverted flex section 14 of the crests 13 toachieve a struccontinuous self-supporting ture having very highproperties of flexibility and resistance to pressure. While theamplitude of the flex section 14 is fairly small in the showing ofFigure 10, it will be understood that a greater flex section amplitudemay be employed without departing from the spirit of the presentinvention.

When convoluted tubing of the types hereinabove discussed is bentsharply there is a tendency to crush the convolutions lying along theinner radius of the bend. As a result of the trough and crest structureshereinabove described, it has been found that damage to the tubingresulting from such bending has been substantially decreased.

From the foregoing it will be seen that there have been providedconvoluted tubing structures by means of which greater internalpressures can be controlled. In addition, tubing structures have beenprovided having greater dimensional stability and wear properties. Theabove described structures are also capable of a wide variety ofperformance characteristics unknown in the present state of the art.

Having thus fully described the invention, what is claimed as new anddesired to be secured by Letters Patent of the United States, is:

1. A convoluted flexible tube structure comprising a continuousfluid-tight member, said member being annularly corrugated into a seriesof troughs and crests of equal amplitude and an annular flex sectionformed in each of saidcrests, said flex section consisting of aninwardly disposed annular convolution having an amplitude smaller thanthat of the troughs and crests.

2. A convoluted flexible tube structure comprising a fluid-tight member,said member being annularly corrugated into a series of troughs andcrests, flattened portions at the roots of said troughs,

and inwardly disposed flex sections in each crest, a series of spacedribs in said troughs and in which the crosssectional form of each troughis dissimilar to the cross sectional form of each of the crests.

References Cited in the file of this patent UNITED STATES PATENTS947,229 Fulton Jan. 25, 1910 2,068,022 Hammel Jan. 19, 1937 2,085,563Aime June 29, 1937' 2,244,847 Oeckl et al June 10, 1941 2,489,277Faralla Nov. 29,1949 2,609,002 Meissner Sept. 2, 1952 2,623,121Lovel'idge Dec. 23, 1952 2,695,631 Seek Nov. 30, 1954 2,739,616 DuflMar. 27, 1956 FOREIGN PATENTS I- 139,164 Germany May 24, 1901 801,603France Ian. 15, 1951' 959,386 Germany Mar. 28, 1950

